Separator



June 19,1934, A, GHR 1,963,469

SEPARATOR Filed April 5, 1929 n J: K

i I /7ll .7nf77 for.

Patented June I9, 1934 SEPARATOR Albert Kiihr, Goeggingen, Germany, assignor to the firm Alpine Aktiengesellschaft, Eisengiesserei Bayern, Germany und Maschinenfabrik,

Augsburg in Application April 5, 1929, Serial No. 552,799 In Germany April 7, 1928 3 Claims. (01. 209-139) This invention relates to separators or sifters and has particular reference to improvements in such apparatus along the lines of increased efiiciency of operation, greater output, improved 5 quality of output, etc.

An important object of the invention relates to the separation'of pulverized material, for example, ground wheat into fine and coarse grades.

Two systems of separators or sifters are mainly known, in which the separation of the fine flour from the grits is effected by an air-current cir-' culating inside of the sifter. In the one system, the fan or ventilator occupies the highest position in the sifter-casing, i. e. being disposed above the sifting-chamber, aspirating the fine flour and blowing the same directly into the flour-chamber, while the grits drop from the sifting-chamber into the grits-hopper. In the second system, the ventilator is disposed below the spreading-plate and forces the material to be sifted upward within a comparatively high inner cylinder, whereby the coarser particles drop along the cylinder-wall into the grits-hopper, while the fine flours are conveyed over the upper edge of the internal cyl- 2 inder to the flour-chamber. Both systems have considerable disadvantages for sifting to utmost fineness. In the first system the distance between the spreading-plate and the ventilator must not be too great, in order to obtain a fair 3 capacity, as some part of the coarser flour is still sucked-up and forced into the flour-chamber, so

' that the fineness of the sifted product cannot be increased beyond a certain degree. In the second system however the entire material to be sifted,

i. e. grits and fine flour are blown-up together. A

separation of the finest flour is therefore rendered difiicult, if the sifter is not worked with a very slow blast of air. Even then, except for extremely small capacity, it is difficult to prevent 4 the passage of the coarser particles into the flour chamber.

These disadvantages of both the above systems are avoided by the separator according to the present application.

4 This separator is equipped above a lower sifting-chamber with a ventilator or fan structure, and an upper siftingand expansion-chamber, according to the present invention, is provided above the ventilator. The fundamental feature 5 of the invention consists therefore of the disposition of the ventilator between a lower siftingchamber (preliminary sifting-chamber) and an upper siftingand expansion-chamber, wherein a subsequent sifting is effected by expansion of 5 the air containing the previously sifted material,

upwards against the inner wall of an outer cylinder and these coarser particles being returned to the grits-chamber alongthe annular space between the inner and outer cylinders of the separator, while the finest particles of the sifted material are conveyed from the upper expansionchamber, over the upper edge of the outer cylinder and then into the flour-chamber. 55

By means of the separator according to the present invention, extraordinary high degrees of fineness can be obtained. Most of the known separators yield a product, which leaves upon a sieve of 5000 meshes per sq. cm. generally a residue of from 5-6% and with a very few, under considerable consumption of power, somewhat finer sifted products are obtainable. Degrees of fineness can, with the sifter according to the present invention, be obtained under extraordi- 76 nary small consumption of power and corresponding to a sieve of 10000 meshes per sq. cm., and products have even been obtained which left upon a sieve of about 17000 meshes per sq. cm. only traces of residues. This extraordinary fa- 80 vorable effect is obtained by the generally advantageous design of the apparatus, by the location' of the fan, by the provision of the passage between the walls of the upper sifting-chamber and the walls of the expansion-chamber in which passage the air is moved downwardly so that the coarser particles separated above the fan are quickly conveyed to the grit hopper.

A separator, according to the present invention, is illustrated in vertical section in the accompanying drawing by way of example.

The sifter is in usual manner fitted in an outer casing or cylinder m with a charging-aperture k, in which a shaft n with a spreading-plate 0 at its lower end is revolving.

This spreading-plate throws the material against a cone-shaped ballling-ring p, which has the purpose of loosening the material and deflect ing the same downwards. From here, the material to be sifted is aspirated through the pre- 10o liminary sifting-chamber q by a ventilator a having blades b disposed obliquely outward. In

the space q preliminary sifting takes place, as

the coarser grits-particles drop along the wall of the cylinder 1 surrounding the ventilator and downinto the grits-hopper e.

According to the invention the ventilator a, b producing a circulating air-current 'in the sense of the drawn arrows, blows the sifted material not directly into the flour-chamber h, but into 11 an upper sifting-chamber 0 above the ventilator. This chamber is formed thereby, that the cylinder 2', surrounding the ventilator a, b, ends with its obliquely inward directed wall a considerable height 1 above the ventilator a, b. The cylinder i has a wall s extending inwardly therefrom, this wall 3 dividing the conduit structure into upper and lower chambers. In a sense and independently of said wall s, the ventilator or fan structure a, 1) also divides the conduit structure into upper and lower chambers. Beyond cylinder 1', an outer, concentric disposed cylinder g projects upwards to a considerable extent. l'he distance I defines substantially the height of the upper sifting-chamber 0 while the distance fl defines substantially the height of an expansionchamber 01. In this expansion-chamber cl further sifting of the already fine flour aspirated by the ventilator is effected by expansion of the air, whereby the coarser particles are separated from the finest.

An annular space d is provided in this manner between the two cylinders g and i. A suction effect or downward movement of air is created, during operation, in this annular space at whereby coarse particles, which are blown outwardly up and against the inner tapering wall of the cylinder i, are drawn quickly down into the grit hopper e.

Finer particles which are blown with the circulating air current beyond the upper siftingchamber 0 enter the expansion-chamber cl, in which further sifting takes place due to the expansion of the air currents, thereby effecting a still more differentiated separation of coarse particles from the finest particles. The coarser particles pass along the inner wall of the cylinder g and into the annular space d whereby they are drawn ofi into the grit hopper e as described, while the finest product is conveyed over the flanged upper edge 1 of the cylinder 9' and, pass by way of the flour space it, into a suitable receptacle provided below the discharge opening. The flange r at the upper end of cylinder g projects toward the interior of said cylinder 9 and assists in the separating action, said flange r catching coarser particles and causing them to pass into the annular space d.

It will be seen from the foregoing that the present invention is concerned with a very emcient sifter in which double sifting is efiected, i. e., a preliminary sifting below the ventilator, and further sifting beyond the ventilator, due to the very advantageous location of the ventilator and its employment as an aspirating device (for the preliminary sifting) and as a blowing device (for the subsequent sifting). It will also be seen that the provision of the two co-axial cylinders g and i, and their particular shapeand relation to each other, providing the annular space d for carrying off coarse particles after the preliminary sifting, increases the effic'iency of the apparatus considerably, without in any way adding complications to the general structure.

While the invention has been described with respect to a certain particular preferred example which gives satisfactory results, it will be understood by those skilled in the art after understanding the invention, that various changes and modiasagna fications may be made without departing from the spirit and scope of the invention and it is intended therefore in the appended claims to cover all such changes and modifications.

What is claimed as new and desired to be secured by Letters Patent is:

1. In a separator, an outer casing, a substantially vertical open-ended conduit structure, means in said conduit structure for loosening and for distributing the material inserted therein, means for dividing said conduit structure into upper and lower chambers, and a fan structure above and adjacent said last-named means for creating suction eifectlve in the lower chamber and radially circulating pressure efiective in the upper chamber, the upper part of said conduit structure being substantially free from obstruction to define a free sifting chamber disposed above said fan structure, said fan structure caus ing the finer material to pass upwardly through said sifting chamber, then outwardly over the upper open end of said conduit structure, and then downwardly on the exterior of said conduit structure.

2. In a separator, an outer casing, a substantially vertical open-ended conduit structure, means in said conduit structure for loosening and for distributing the material inserted therein, means for dividing said conduit structure into upper and lower chambers, bafiie means associated with said dividing means and extending into said lower chamber, and a fan structure above and adjacent said dividing means for creating suction effective in the lower chamber and radially circulating pressure effective in the upper chamber, the upper part of said conduit structure being substantially free from obstruction to define a free sifting chamber disposed above said fan structure, said fan structure causing the finer material to pass upwardly through said sifting chamber, then outwardly over the upper open end of said conduit structure, and then downwardly on the exterior of said conduit structure.

3. In a separator, an outer casing, a substantially vertical open-ended conduit structure, said conduit structure comprising inner and outer conduits disposed substantially coaxially to form an annular space and the upper end of the inner conduit terminating below the upper end of the outer conduit, means comprising a fan structure disposed below the upper end of said inner conduit for dividing said conduit structure into serially related and coaxially disposed upper and lower chambers, the upper part of said conduit structure being substantially free from obstruction to define a free sifting chamber disposed above said fan structure, and means in the lower chamber for loosening and for distributing the material inserted therein, said fan structure creating suction efiective in the lower chamber and radially circulating pressure eifective in the upper chamber, said fan. structure causing the finer material to pass upwardly through said upper chamber, then outwardly over the upper open end of said conduit structure, and then downwardly on the exterior of said conduit structure.

ALBERT KfIHR. 

